Container assemblies for releasing an agent into a container at a desired point in time are well known and come in many shapes and sizes, both within the industry as well as within consumer goods.
In hospitals and clinics containers or Petri dishes are used for collecting and storing tissue samples, such that after a tissue sample has been taken from a patient, the tissue sample is placed in a container, and a preserving agent, often formalin, is subsequently filled in the container before the container is closed and sent off to a laboratory for analysis. Here the container is usually opened in a fume cupboard as formalin and other preserving agents are toxic to inhale. The problem with this is that in the hospital the personnel taking the tissue sample, have to handle a preserving agent on a daily basis when filling the container. Usually a formalin dispenser station or a dispenser mountable on the container temporarily is used. After the formalin has been dispensed into the container, the lid is mounted on the container. Handling of a preserving agent this way may result in spillage and inhalation. Inhalation and other exposures constitute is a health hazard and handling of formalin and other preserving agents should be carried out with great care.
WO2004/000678 describes different embodiments of mixing vials, in particular the embodiment depicted in FIGS. 6A-B show a mixing vial where a rigid rod is pressed through a supplemental container and the dilutant is entered into the container.
U.S. Pat. No. 5,152,965 describes an assembly of containers, comprising a reagent vial and a container adapted to engage with an adapter assembly positioned between the two. The reagent vial contains a reagent to be mixed with a reagent diluent in the container. The adapter assembly comprises a coupler and a hollow plunger. The reagent vial is engageable with the coupler in a first position and is advanceable into a second position relative to the adapter assembly such that the hollow plunger thereof displaces the seal of the reagent vial permitting the reagent to flow through the hollow plunger to mix with diluent in the container.
The advancement of the coupler results in an increased pressure in the container, which is undesirable as the increased pressure might result in a spillage of the content in the container, when the adapter assembly is removed from the container.
WO2008/040812 describes a receptacle configured to receive a volume of preserving agent, and a lid containing the preserving agent and being adapted to be coupled to a tissue storage container. The preserving agent is entered into the lid through a one way valve. The lid further comprises a membrane with a number of holes. A plastic disc containing an equal amount of holes is placed between the receptacle and the membrane in the lid. When the holes are brought into alignment, e.g. by twisting the lid, the preserving agent flows into the receptacle. This requires that the container assembly is oriented such that the cover facing upwards, thereby allowing the preserving agent to flow into the container assisted by gravity.